In co-pending application U.S. Ser. No. 945,743 filed Dec. 23, 1986 the instant delivery system was used to deliver sweeteners. Also in co-pending application U.S. Ser. No. 270,892 it was found that the present delivery system using low molecular weight polyvinyl acetate could be utilized to deliver food acids. It has now been discovered that the delivery system also has the capability of delivering food acids over an extended chewing period utilizing polyvinyl acetate with higher molecular weights up to and exceeding 50,000.
The art has disclosed the addition of food acids to chewing gum compositions in order to achieve the desired sourness effect, particularly in citrus fruit flavors. Generally, the acids are added directly to the water-soluble chewing gum portion of the chewing gum composition to ensure the release of the acid during mastication. For Example, U.S. Pat. Nos. 4,088,788 and 4,151,270, both to Ream et al. disclose the addition of at least 3% by weight of one or more organic acids in combination with a sweetener to achieve an alleged synergistic saliva stimulating effect. The acids disclosed are added directly to the gum composition in their free form without mention of coating or encapsulation.
Another example of the use of food acids being added directly in their free form to a chewing gum composition is disclosed in U.S. Pat. No. 4,085,227 to Mackay et al. This patent disclosed both poorly water-soluble and water soluble food acids being added to the gum base portion of the chewing gum composition. According to the disclosure of this patent, the acids must be in the particle range of less than 150 microns. Numerous gum base materials are mentioned, among which is polyvinyl acetate. Gum base is disclosed as being present in amounts of about 10-50% by weight. No specific range of molecular weight is mentioned with regard to gum base elastomers in general or specifically to polyvinyl acetate.
Another example of the incorporation of free acids in a chewing gum composition is U.S. Pat. No. 4,800,191 wherein a gum is disclosed with prolonged juiciness and flavor through the incorporation of a premixed blend of acids having different organic/aqueous partitioning coefficients such that they have sequential release rates during mastication.
Although the art has concentrated on direct addition of food acids to chewing gum rather than encapsulation of the acid, encapsulation is disclosed in U.S. Pat. No. 3,795,744 to Ogawa et al. This patent discloses various "seasonings," among which are included acidifying agents, the "seasonings" being coated or encapsulated with high molecular weight compounds. Among the encapsulating compounds disclosed are: starches, cellulose, proteins, gums, polyvinyl alcohol, low molecular weight polyethylene and polyvinyl esters such as polyvinyl acetate, polyvinyl propionate, a graft-copolymer of polyvinyl propionate and polyvinyl acetate, a copolymer of vinyl acetate and ethylene, propylene, acrylic and methacrylic acid, crotonic acid, maleic acid and esters of unsaturated acids thereof. The polymers have a polymerization degree of 200-1500 and their mixtures are also disclosed as being useful.
The claims of the Ogawa reference are directed to a method of preparing a chewing gum which can variably release different flavors due to the encapsulated "seasoning" particles comprising the steps of: dissolving about 2-30% by weight polyvinyl ester in a solvent selected from the group consisting of ethanol, ethylacetate and mixtures thereof, and homogeneously dispersing a flavor agent in the amount of 1-20 times the weight of the polyvinyl ester content; adding to this first solution a second solvent which is miscible with said first solvent but is a nonsolvent for said polyvinyl ester, said second solvent being selected from the group consisting of hexane, whereby said polyvinyl ester precipitates out in the form of discrete particles which encapsulate the "seasoning," e.g. food acids. These encapsulated particles are added to a chewing gum composition.
In addition to the above-mentioned art concerning the addition of food acids, the use of encapsulated sweeteners and flavors in chewing gum compositions is well known. Numerous patents have disclosed coatings for sweeteners in an attempt to delay or prolong sweetness, as well as to stabilize those sweeteners, such as aspartame, which are sensitive to moisture, temperature and pH. U.S. Pat. No. 4,384,004 to Cea et al., discloses solid particles of aspartame encapsulated by a coating material selected from the group consisting of cellulose, cellulose derivatives, arabinogalactin, gum arabic, polyolefins, waxes, vinyl polymers, gelatin, zein and mixtures thereof, wherein the amount of said coating material to said methyl ester is from 1:1 to 1:10. More particularly, the coating materials include cellulose, methyl cellulose, ethyl cellulose, cellulose nitrate, cellulose acetate phthalate, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, arabinogalactan; polyethylene, polymethacrylates, polyamides, ethylenevinyl acetate copolymers, polyvinylpyrrolidone; gum arabic; paraffin wax, carnauba wax, spermaceti, beeswax; stearic acid, stearyl alcohol, glyceryl stearate; gelatin, zein and mixtures thereof.
The method of coating employed in the Cea et al reference includes suspending the aspartame particles in a stream of air that passes through a zone of atomized liquid droplets of the coating material, so that the coating material is deposited on the surface of the aspartame. More than one coating may be used whereby the inner coating is water-soluble and the outer coating is water-insoluble.
U.S. Pat. No. Nos. 4,122,195 and 4,139,939, both to Bahoshy et al., fix aspartame by preparing it with a material such as gum arabic or the reaction product of a compound containing a polyvalent metallic ion, with an ungelatinized starch acid-ester of a substituted dicarboxylic acid, by a spray drying technique, where the aspartame and a film former are prepared in an emulsion.
U.S. Pat. No. 4,374,858, to Glass et al., discloses an aspartame sweetened chewing gum having improved sweetness stability wherein the chewing gum piece has aspartame coated on its surface, as opposed to incorporating it in the chewing gum mix.
EPA 81110320.0, published June 16, 1982 (Publication No. 0,053,844), to Ajinomoto Co., Inc., discloses a stabilized depeptide-based sweetening composition comprising (a) from 20 to 60% by weight of solid fat, (b) from 10 to 30% by weight emulsifier, (c) from 10 to 30% by weight polysaccharide and (d) not more than 30% by weight of dipeptide sweetener. The compositions are prepared by heating the mixture of the ingredients, cooling, and pulverizing them in order to obtain a powder or granule of the composition with an ASTM mesh size of smaller than 12. Spray drying the mixture is also disclosed.
U.S. Pat. No. 4,105,801 to Degliotti, discloses a confectionery comprising a core portion and a shell adheringly enveloping the core portion, whereby the shell is formed by an intimate mixture of microcrystals of xylitol with a solid fatty substance in a proportion of 0.5 to 15 parts by weight of fatty substance to each 100 parts by weight of xylitol. The fatty substance is preferably a mono-, di- or triglyceride having a melting range of between 20.degree. and 60.degree. C.
U.S. Pat. No. 3,389,000 to Toyonaka et al., discloses protective coatings for granular nucleoside-5-phosphates, the coatings being edible fats melting between 40.degree.-100.degree. C. and derived from plants and animals. Examples of hydrogenated oils used are soybean oil, cottonseed oil, almond oil, castor oil, linseed oil, mustard oil, olive oil, grapefruit seed oil, palm oil, palm kernel oil, rapeseed oil, rice bran oil and the like and mixtures thereof. This reference discloses a process of preparing the granular product from a liquid mixture of fats and nucleoside-5-phosphates which are sprayed from a pressure nozzle and the resultant granules cooked and recovered.
U.S. Pat. No. 4,382,924, to Berling, discloses liquid oral dosage forms for vitamins or pharmaceutical materials comprising an edible oil, a high potency lipid soluble sweetener such as saccharin and a lipid soluble flavorant. The edible oil may be a polyol fatty acid ester having at least four fatty acid ester groups and each fatty acid having from about 8 to about 22 carbon atoms. The oil, sweetener and flavor oil are mixed and heated and then cooled to provide a palatable liquid dosage form.
For a general discussion of spraying fatty materials onto sweeteners and the like see U.S. Pat. Nos. 3,949,094 and 3,976,794 both to Johnson, and U.S. Pat. No. 3,867,556 to Darragh. U.S. Pat. No. 4,293,572 to Silva et al., discloses the application of a dispersion of an emulsified fat with a solution of dextrin, saccharin or a polysaccharide to a food product as a barrier against moisture. U.S. Pat. No. 3,527,647 discloses a process of agglomerating particles by randomly scattering and spraying moistened particles to cause them to collide and form agglomerates.
The problem relating to stabilization of certain core materials relates to the surface wettability of the material as well as to its morphological configuration. For example, in the case of certain sweeteners, this is of particular importance. Aspartame is known to be rod-like, needle-like or dendritic in shape. As a result it is very difficult to coat aspartame using ordinary mixing or spray coating techniques. To be effective as protective barriers, coatings must be able to wet and adhere to the crystalline surface, including the needle-like tips and other shape variations of the aspartame. Additionally, the coating must be capable of being applied in a film with a uniform thickness sufficient to provide a barrier against degradative factors such as moisture, pH changes, temperature changes and reactive chemicals. The coatings, in addition to being protective barriers, must be flexible enough to conform to the surface irregularities and geometrical configuration without cracking due to mechanical stresses which it is subjected to during incorporation of the sweetener into specific product applications. Attempts to coat aspartame using spray techniques to apply simple mixtures of fat and lecithin have resulted in poor wetting, spotty coating and inadequate protection against moisture and other potentially degradative factors.
The process of EPA 81110320.9 (Publication No. 0053844) filed Dec. 10, 1981, discussed above, is an example of simple admixing of coating materials with aspartame. This publication discloses the simple melting and admixing of from 20 to 60% of solid fat,10 to 30% of emulsifier, 10 to 30% of polysaccharide and not more than 30% dipeptide sweetener. The mixture is then cooled and pulverized or spray dried. The pulverizing of the mixture into fine powder, however, results in a rupturing of the coating, leaving the aspartame exposed. Spray drying is normally associated with the driving off of moisture or solvents.
U.S. Pat. No. 4,597,970 discloses a delivery system wherein a sweetener is coated with a mixture of fatty acid or wax, lecithin and monoglyceride.
The instant invention seeks to provide coating compositions which eliminate the need for the fatty acid or wax component, yet still provides adequate protection and delayed release of the sweetener, food acid or other actives contained therein.
The prior art techniques for coating difficult to coat materials such as food acids or aspartame, has focused on two methods. The first method involves the formation of a molten mixture of the coating material with the sweetener. The mixture is then solidified by cooling and pulverized. The resultant particles represent a random attempt at completely coating or enrobing the sweetener. In the case of aspartame, this coating does not provide adequate protection against moisture or aldehyde-containing flavor oils and instability of the aspartame results.
The second conventional prior art technique for coating materials involves fluidized bed spray coating. This technique involves suspending a mass of the material to be coated into a stream of atomized droplets of coating material. In the case of materials such as aspartame, this method is very difficult. Aspartame is a low density material, has a large surface area to weight ratio and poor wetting characteristics. For these reasons, spray coating of aspartame in a fluidized bed system is difficult.
The instant process is an improvement over spray congealing techniques and includes additional coating steps. The resultant product exhibits a marked improvement in the effectiveness of the coating as a protective barrier by tailoring the type of polyvinyl acetate selected to the type of food acid sought to be encapsulated. The result is a significant improvement in the controlled and sustained release of the core material.
Thus, the delivery systems of the invention and process of preparation provide an improved protective coating which results in a controlled sequential release of the core materials such as food grade acids. The delivery systems have a variety of other advantages including the controlled release of other materials such as sweeteners and flavoring agents. Other advantages will become apparent herein.